PHYSICAL CHARACTERIZATION OF RECOMBINANT TISSUE-PLASMINOGEN ACTIVATOR

Electron microscopic and physical-chemical properties of one- and two- chain tissue plasminogen activator (t-PA) were studied. The molecular weight of one-chain t-PA obtained by both sedimentation equilibrium an d SDS-PAGE was estimated to be about 65000, while both chains in the r educed two-chain form were in the range of 35000-40000. Sedimentation coefficients were identical for both forms of t-PA (S20,w0 = 4.12). Th e two forms of t-PA were indistinguishable by electron microscopic ana lysis, which confirmed the sedimentation results, and showed that they were ellipsoidal end relatively compact. The major and minor axes wer e approx. 13 nm and approx. 10 nm and f/f0 was 1.36. The individual do mains of t-PA are relatively small and are folded within the molecule, so that the overall appearance is globular.